Book Review

Title: Introduction to Electromagnetic Compatibility, 2nd Edition
Author: Clayton R. Paul
Publisher: Wiley Interscience
Publication Date: 2006
Number of Pages: 983

 

 

This review addresses the second edition (2006) of the well-known book by Prof. Clayton Paul, Introduction to Electromagnetic Compatibility, which first appeared in 1992. Though I had personally read his first book, I decided to read the new book, all over again. It took me about one month, in my spare time, to read the almost 1000 pages of this new text (previous edition was about 750 pages). As I was reading the text I tried to put myself in the shoes of a senior undergraduate or first year graduate student and ask myself the question, “Would I understand this if it were my first experience with the subject?” In the same spirit, I also worked a problem from each chapter of the book and asked myself the same question. The answer to both questions was indeed YES. The attention to all the technical details in this book is extraordinary. The harmonization of the contents among all the chapters to provide a progressive theme in EMI and its control is amazing. This book was truly written with the student in mind. It is indeed a classic in terms of the undergraduate teaching of EMC at the college level.
The second edition of this book has been substantially revised and re-written from the first edition. For example, the student will enjoy a large number of worked examples in just about every section of each chapter in the book. Each section of each chapter also has a review exercise for the student to test the knowledge of what the important technical points for that section is about. Just about every problem in the back of each chapter has the answers given, so the student can corroborate his/her effort. Most of the problems are new. Chapters have also been repositioned (from the first edition), which allow the flow of knowledge to build up in a more uniform and logical fashion. Another thing the student will enjoy is the use of PSPICE in many of the worked examples as well as in many assignments of several chapters. PSPICE is introduced, in a given chapter, to corroborate the theory the students have learned and how the PSPICE modeling tool can be used to model more complicated examples; hence, the book emphasizes the use of PSPICE to simulate all areas of EMC analysis. The students will also see that the book contains a CD ROM with OrCAD PSPICE version 10 and MicroSim PSPICE version 8 (student versions) as well as several FORTRAN programs written by the author to compute per-unit-length parameters and also programs for the analysis of crosstalk in multiconductor transmission lines. Though I did not have time to try it, it would not be difficult to convert these programs to VBasic and run using Excel. Faculty will also enjoy this book because it simply makes teaching EMC much easier; it is that simple. Because of my limited amount of space in the Newsletter, as I review each chapter, the emphasis will be on addressing the content (i.e. what is covered in the chapter; I will leave the discussions of EMC and the technical issues to the reader). Nevertheless, I must emphasize that the explanations of all the EMC principles are presented in satisfying detail.
The book is made up of nine chapters and four appendices. Appendix C is of special interest because it describes seven FORTRAN programs in the CD for calculating per-unit-length parameters and crosstalk analysis (with the help of PSPICE).
Chapter 1 titled Introduction to Electromagnetic Compatibility is an introduction to the reader to the concepts of electromagnetic compatibility; the how and why EMI happens, some history of EMC, an introduction to electromagnetic waves, and a discussion on how we arrive at the common EMC units (dB, dBuV, dBuA, dBmW, etc.) with some practical examples (e.g. the treatment of power loss in cables, and signal source specifications). Chapter 2 titled EMC Requirements for Electronic Systems is a highly revamped version from the first edition and it addresses the EMC requirements for electronic systems. This was highly necessary since there has been a lot of US and other governmental changes in EMC requirements since the first edition was published. Therefore, the chapter contains the latest conducted and radiated emission requirements for US (FCC) and European (CISPR 22) commercial computing devices, and also the latest conducted and radiated emission requirements for US military standards (MIL-STD-461E). In addition to the requirements, the chapter covers measurements methods for radiated emissions (using OATS, semi-anechoic chambers) and conducted emissions (using the LISN) measurements. The chapter briefly covers susceptibility and ESD requirements. The chapter ends with some qualitative analysis of the importance of EMC in the design process of a product and some of the constraints and considerations that arise during that process.
Chapter 3 titled Signal Spectra—The Relationship between Time and Frequency Domain is one of those repositioned chapters I talked about before. It went from Chapter 7 in the first edition to now Chapter 3. The author was correct. This is the right location for this chapter since the material in it serves as the backbone for the rest of the book. The material of this chapter is similar to what a junior electrical engineer student will see in a Signals & Systems course (i.e. spectra of periodic and non-periodic and random signals). However, the material is tailored to the type of signals present in typical digital products. One unique feature of this chapter (and to me the most important) is that it develops “bounds” for the different types of spectra which facilitates the analysis of the effects of these signals (several good examples are given), a concept that most EMC engineers must grasp if one wants to make quick assessments of what types of EMI violations might be present in a given product. The chapter also addresses measurement equipment such as the spectrum analyzer and how it works in light of the material covered in this chapter. The chapter ends with the use of PSPICE in Fourier analysis and several very illustrative examples are provided.
Chapter 4 is titled Transmission Lines and Signal Integrity. This chapter has been significantly revised when compared to the first edition because it now includes signal integrity. This chapter, together with Chapter 3, are a must for future EMC engineers to master, and the rest of the book really depends upon the concepts developed in these two chapters. I believe these are the two most important chapters in the book. The treatment of signal integrity is necessary because at today’s computing device frequencies, the physical size of transmission lines (wiring, traces, etc.) are now comparable in size to the wavelength of the circuits’ operating frequencies (or at least the wavelengths of the harmonics). Therefore, these physical transmission lines must now be treated as true transmission lines. The chapter starts with the general two-conductor transmission line and then goes on to address how to derive the per unit length parameters (inductive and capacitive) and the characteristic impedance of such a transmission line. Information is provided for different physical topologies such as round wires (next two each, above ground, and shielded) and printed circuit board lands (stripline, microstrip, PCB strips). The two-conductor transmission line is analyzed in the time domain and frequency domain. The analysis in the time domain includes the graphical solution approach (basically an analytical approach) and the SPICE model. The time domain analysis is extended to address the development of transmission lines models for signal integrity purposes. Both analytical and SPICE modeling examples are illustrated. The chapter ends with modeling the two-conductor transmission line also in the frequency domain, which allows a better introduction for modeling the effect of losses in signal integrity. The chapter ends with the usage of SPICE for modeling the transmission line in the frequency domain as well as using the lumped circuit approximate model.
Chapter 5 is titled Nonideal Behavior of Components and it has been expanded from the first edition. This chapter develops mathematical models that provide considerable information on the nonideal behavior of components (resistors, capacitors, inductors) and conductors (PCB lands, component leads) at higher frequencies (frequencies that may go beyond the applicable government regulations but still must be accounted for because of the needed self compatibility of the product). It is here that the chapter introduces several concepts (e.g. skin depth, internal inductance, external inductance, line capacitance, characteristic impedance, loss tangent) for wires and PCB lands that will be used later in subsequent chapters. The nonideal behavior of certain components actually provides advantages in reducing noise. To that end, the chapter provides techniques for either diverting or diminishing noise at these higher frequencies. For example, the chapter addresses in detail the principles of using capacitance to divert noise for high impedance loads (it does not work for low impedance loads) and the use of ferromagnetic materials (ferromagnetic cores, ferrite beads, common mode chokes) for diminishing noise, especially common mode noise. It is during the discussion of common mode chokes that the book discusses, for the first time, the concepts of differential mode and common mode currents, a concept that is explained in more detail again in Chapters 6 and 8. I thought the introduction of common mode currents in this chapter was strategically correct and well placed. The chapter ends by addressing the noise from electromechanical devices (motors, solenoids, and mechanical switches).
Chapter 6 is titled Conducted Emissions and Susceptibility and is essentially the same as the first edition of the book. The purpose of the chapter is to investigate the ways by which emissions are generated and propagated through conducted paths along the product’s ac power cord. Conducted emissions from power distribution systems can also radiate and make such cabling behave as antennas. The main emphasis in the chapter is the measurement and control of conducted emissions. A more detailed explanation of the LISN is given. The chapter also addresses in more detail the concepts of common mode and differential mode currents. From the control of emissions point of view, the author discusses the basic design, topology, workings, and EMI suppressing features of power supply filters. Now the two concepts of common mode currents and conduction EMI filtering come together in the chapter, as the effects of filter elements are studied with respect to common mode and differential mode currents, and how to separate the conducted emissions measurements into common mode and differential mode. Example measurements are given. The chapter ends with a discussion on the topology and designs of different types of common power supplies (linear and switching mode), and how the common mode currents can manifest themselves in these types of power supplies.
Chapter 7 titled Antennas is essentially the same as the first edition of the book. This chapter is addressed because the reader needs to be familiar with the typical antennas used in EMC measurements. This will provide the ability to calculate the electromagnetic field levels in the vicinity of the product that will be used to determine its susceptibility to interference. This topic is also addressed because of the fact that radiated emissions are produced by unintentional antennas and there is a need to understand how to approximately model these antennas. The material starts with the coverage of the simplest of all radiating elements, the Hertzian and the magnetic dipoles, followed by the half-wave dipole and the quarter-wave monopole. All analysis is presented in the far field and includes the calculation of the radiated electric/magnetic fields, average radiated power, and radiation resistance. The analysis for general antennas is extended also to antenna arrays. The chapter then addresses other types of antenna parameters such as directivity, gain, effective aperture, and antenna factors (a terminology very familiar to EMC test engineers). There are a few examples presented on the usage of antenna factors. A very simple model on the coupling of two antennas is addressed using the Friis model. Because it is important to EMC testing, the effect of reflections of EM waves and multipath effects is also addressed. The chapter ends with an overview of the biconical and log periodic antennas (the mainstay antennas for EMC testing).
Chapter 8 has been slightly revised in this second edition. The chapter is titled Radiated Emissions and Susceptibility. The objective of the chapter is to use some of the modeled radiated electric fields presented in Chapter 7 (Hertzian and half-wave dipole) to postulate radiated emissions models (far field only) from simple unintentional radiating elements like wires (e.g. those found in I/O cabling) and PCB lands. This chapter expands upon the concepts of differential mode and common mode currents addressed in previous chapters. The chapter presents models for radiating wires/lands where the currents are initially differential mode and then are common mode. Through several examples, the chapter shows that common mode currents often are the culprits in radiating structures producing the majority of radiated emissions, even though the common mode current themselves may be small. The chapter shows how to measure the common mode and differential mode currents using current probes. Several examples are also given. The chapter ends with simple field-to-wire coupling models and a few examples of such.
Chapter 9 is the largest chapter in the book and is titled Crosstalk. The chapter has been substantially revised from the first edition. Crosstalk is a near field-coupling problem. The material in this chapter is very detailed. This chapter, as important as it is, is an extension of previous chapters dealing with 2-conductor transmissions lines; whereas in crosstalk we deal with a 3-conductor transmission line where the third conductor is the “receptor” or victim of the crosstalk; and the objective is to calculate the induced near-end and far-end voltages given the line cross-sectional dimensions and the termination characteristics of the line. The MTL lossless equations are again developed with assumed TEM propagation. The next step is to develop all the per unit length parameters. The chapter uses both, closed form expressions (wires are separated sufficiently) and numerical methods (method of moments) for closely spaced wires. The chapter does a very detailed job in this area and includes FORTRAN programs that compute the per unit length parameters for ribbon cables, PCB lands, coupled microstrip lines, and coupled strip lines. The chapter develops, in the frequency and time domains, the inductive-capacitive coupling model in a very elegant way (intuitively and mathematically), and this is done for unshielded and shielded conductors. Throughout this development, the chapter presents numerous examples and provides corroboration with experimental results. The chapter also contains a FORTRAN program (on the CD) that contains an exact PSPICE subcircuit model for a coupled transmission line and it is used in numerical and experimental examples.
Chapter 10 is titled Shielding. It is essentially the same as in the first edition. The chapter addresses the subject form an “enclosure” point of view and the main objective is how to calculate the shielding effectiveness of a shielded structure under different conditions (far field, near field) and also the effects of apertures on the shielding effectiveness.
There is a new final Chapter in this edition. Chapter 11 is titled System Design for EMC. This chapter encourages the engineer to take a systems approach to addressing EMC in a product design. The objective of this final chapter is to provide applications of the material learned in previous chapters. I find the contents of Chapter 11 to be relatively pleasant reading after the technical rigorousness of previous chapters. Of extreme importance, and almost required reading, is the section on grounding. I found this section to be one of the most insightful in the entire book.
I would certainly use this book for the teaching of EE undergraduates or first year EE graduate students on the subject of EMC. I highly recommend this book. EMC


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